Study of the pedigree of a patient with type 3 hyperlipoproteinaemia and sinking prebeta lipoprotein.

A 49-year-old woman, suffering from peripheral vascular disease, was found to have two lipoprotein abnormalities, namely, type III hyperlipoproteinaemia and sinking prebeta lipoprotein. Twenty-one members of the kindred were investigated in an attempt to determine the pattern of inheritance of both of these abnormalities. In a 21-year-old son of the proband plasma electrophoresis was in keeping with a type V hyperlipoproteinaemia. It is suggested that this may be a stage in the development of the characteristic type III pattern. If this is so it is consistent with previous suggestions of an incompletely penetrant single autosomal allele. Sinking prebeta lipoprotein was found in the plasma of two other members of the family. If this abnormality is also inherited as a single autosomal allele it must have a very low penetrance and the possibility that the abnormality is acquired cannot be excluded.